In U.S. Pat. No. 4,319,776 issued Mar. 16, 1982 there is disclosed and claimed a security seal formed of a single piece of molded plastic, comprising a pair of legs mounted on a base and carrying on their free ends locking stud and socket members adapted for locking engagement when the legs are flexed together. To cause the stud and socket members to separate if they are not securely engaged, an additional spring is formed which extends between the legs and is flexed when the legs are flexed together. The leg spreading force applied by the additional spring causes the legs to separate if the stud has not securely locked in the socket.